Collision Detecting Device for a Motor Vehicle for Detecting a Collision with a Pedestrian

ABSTRACT

A collision detecting device for a motor vehicle for detecting a collision with a pedestrian has a pressure measuring chamber, which is formed by a tube, and a flexurally stiff structural element. The tube is formed to be deformable in the event of a collision, i.e. as a result of a collision of the motor vehicle with the pedestrian, and is correspondingly arranged. The tube is also supported in a direction, in particular in precisely one direction transverse to a vertical direction of the motor vehicle. In addition, the tube is essentially in particular flexurally stiffly supported on the structural element in precisely one, i.e. in exclusively one, vertical direction of the vehicle.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International Application No.PCT/EP2016/078054, filed Nov. 17, 2016, which claims priority under 35U.S.C. § 119 from German Patent Application No. 10 2015 223 573.4, filedNov. 27, 2015, the entire disclosures of which are herein expresslyincorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a collision detection device for amotor vehicle, in particular a passenger motor vehicle, for detecting acollision with a pedestrian, wherein the collision detection device hasa pressure measurement chamber which is formed by a tube.

In a motor vehicle, in particular a two-track passenger motor vehicle,it is known to arrange between a bumper cover and a front bumpercrossmember an energy-absorption element which, for the purpose ofprotecting a pedestrian, is deformable at a relatively low force levelin the event of a collision of the motor vehicle with the pedestrian. Acollision detection sensor system based on pressure measurement is alsoknown. The collision detection sensor system serves for detecting acollision with a pedestrian, with the result that a control unit canactively direct passenger protection measures, for example the raisingof a front flap or the triggering of a front windshield airbag, based onthis detection. Such a collision detection sensor system has a tube towhich there is connected a pressure sensor which is able to detectpressure variations within the tube. The tube is filled with air underatmospheric pressure. If the tube is deformed as a result of thecollision with the pedestrian, this brings about a change in pressure inthe interior of the tube. Such a tube is normally arranged in thetransverse direction of the vehicle in abutment with the bumpercrossmember and accommodated in a groove in the energy-absorptionelement.

Depending on the configuration of the bumper cover, the bumpercrossmember and/or the energy-absorption element and also the tube,there is a requirement for improving a response behavior of thecollision detection sensor system, that is to say for detecting thecollision at an earlier point-in-time and for improving a strength of adetection signal.

It is the object of the present invention to provide a collisiondetection device for a motor vehicle for detecting a collision with apedestrian, which device improves a response behavior and/or asensitivity during the collision with the pedestrian in a low-costmanner by way of a simple measure.

This and other objects are achieved by a collision detection device fora motor vehicle, in particular for a motor vehicle front end or a motorvehicle rear end, for detecting a collision with a pedestrian, having apressure measurement chamber which is formed by a tube, and having aflexurally rigid structural element, wherein the tube is formed andarranged so as to be deformable in a collision-induced manner and issupported against the structural element in a direction transverse to avertical direction of the vehicle and in precisely one verticaldirection of the vehicle.

The collision detection device according to the invention for a motorvehicle for detecting a collision with a pedestrian has a pressuremeasurement chamber which is formed by a tube, and has a flexurallyrigid structural element. The tube is formed so as to be deformable in acollision-induced manner, that is to say as a result of a collision ofthe motor vehicle with the pedestrian, and is correspondingly arranged.Also, the tube is supported in one direction, in particular in preciselyone direction, transverse to a vertical direction of the vehicle.Furthermore, the tube is substantially, in particular flexurallyrigidly, supported against the structural element in precisely one, thatis to say in exclusively one, vertical direction of the vehicle. “Inprecisely one vertical direction of the vehicle” means that the tube issupported either upwardly or downwardly, but is not supported in both ofthese directions.

The inventors have found that, in the event of a collision with apedestrian, who normally has a center of gravity which is not located ata height of the tube (the center of gravity is normally located above avehicle front end), the collision load on the vehicle front end actsobliquely in the direction of the flexurally rigid structural element.It is therefore advantageous if the tube is supported in a directiontransverse to the vertical direction of the vehicle, and in preciselyone vertical direction of the vehicle, such that both that component ofthe collision load which acts in the vertical direction of the vehicleand that component of the collision load which acts in the directiontransverse to the vertical direction of the vehicle are able to deformthe tube effectively. If the tube were supported in both verticaldirections of the vehicle, that is to say upwardly and downwardly, thatcomponent of the collision load which acts in the vertical direction ofthe vehicle would be unable to deform the tube. Accordingly, bysupporting the tube in precisely one vertical direction, it is possiblefor a collision load acting on the tube obliquely from below orobliquely from above to be detected better, that is to say more quicklyand more sensitively.

The collision detection device is preferably arranged in a motor vehiclefront end, but may also be arranged in a motor vehicle rear end.

“A direction transverse to a vertical direction of the vehicle” means inparticular a direction perpendicular to or substantially perpendicularto a vertical direction of the vehicle. The direction transverse to thevertical direction of the vehicle is furthermore preferablysubstantially a longitudinal direction of the vehicle.

According to a preferred refinement of the present invention, thestructural element has a first support surface which extendssubstantially parallel to the vertical direction of the vehicle, and hasa second support surface which extends transversely to the verticaldirection of the vehicle, for example substantially in a longitudinaldirection of the vehicle.

The second support surface may be formed either on a top side or abottom side of a projection which is connected to the first supportsurface or the structural element in a flexurally rigid manner or whichis formed integrally with the first support surface or the structuralelement, and a lower side of the tube or an upper side of the tube maybe supported against the projection. The term “projection” also covers ashoulder or a step.

The first support surface may in particular be formed behind the tube inthe collision direction, and the second support surface may be formedbelow the tube.

In the case of a motor vehicle front end, this means that the firstsupport surface is formed behind the tube in the main direction oftravel of the vehicle.

The structural element may in this case be a crossmember element, inparticular a bumper crossmember, and the first support surface may beformed on an outer side of the crossmember element, and the secondsupport surface may be formed on a projection which is connected fixedlyin terms of torque to the crossmember element or which is formedintegrally with the crossmember element.

In the case of the front bumper crossmember, the first support surfaceis thus formed on a front side of the bumper crossmember.

According to an alternative advantageous refinement of the collisiondetection device, the first support surface may be formed in front ofthe tube in the collision direction, and the second support surface maybe formed above the tube.

In particular, the structural element may be a vehicle outer skin, forexample a bumper cover, and the first support surface may be formed onan inner side of the vehicle outer skin, and the second support surfacemay be formed on a projection which is connected fixedly in terms oftorque to the vehicle outer skin.

According to a further advantageous refinement of the collisiondetection device, the second support surface may extend along an entireeffective length of the tube.

Alternatively, it is also possible for the second support surface toextend sectionally along the effective length of the tube.

The effective length of the tube is that region of the tube which isprovided for detecting the collision with the pedestrian.

This allows a target response behavior to be suitably adapted to thestructural conditions of the motor vehicle.

According to a further preferred refinement of the present invention, inthe collision detection device, the tube is surrounded at leastpartially by a plastically deformable energy-absorption element or is atleast adjacent to the energy-absorption element, wherein theenergy-absorption element is arranged in front of or behind thestructural element in the collision direction.

This allows the oblique collision load to better deform the tube as aresult of mutual supporting of the tube between the energy-absorptionelement and the structural element, with use made of the components ofthe collision load in a vertical direction and the direction transverseto the vertical direction. In other words, in the event of a collision,the tube is clamped obliquely between the energy-absorption element andthe structural element by way of the obliquely acting collision load.

The energy-absorption element is for example a so-called pedestrianprotection element, in particular a passive pedestrian protectionelement.

The energy-absorption element consists for example of a foam, inparticular a thermoplastic foam, which, for the purpose of protectingpedestrians, is deformable at a relatively low force level.

The energy-absorption element is arranged for example between a vehicleouter skin and a crossmember.

The energy-absorption element may bear against the tube, or at leastcome into abutment with the tube in the event of a collision, on sidesof the tube which are not supported, which are in particular notsupported in a longitudinal direction of the vehicle and in a verticaldirection of the vehicle. In other words, the tube is indirectly ordirectly supported against the energy-absorption element in the other,that is to say opposite, vertical direction of the vehicle, and the tubeis indirectly or directly supported against the energy-absorptionelement in the opposite direction to the direction transverse to thevertical direction of the vehicle.

The tube preferably consists of an extruded plastic material, forexample an elastomer material, in particular a silicone material. Thismaterial is inexpensive and permits an easily deformable tube.

The collision detection device also advantageously has a pressure sensorwhich is arranged such that it communicates with the pressuremeasurement chamber. The pressure sensor is adapted to detect a pressureand/or a change in pressure in the pressure measurement chamber as aresult of the collision-induced deformation of the tube.

Here, “collision direction” identifies the direction in which thecollision counterpart, that is to say the pedestrian, collides with themotor vehicle, that is to say the direction in which the collisioncounterpart exerts a collision force on the motor vehicle.

Above-mentioned refinements of the invention may be combined with oneanother in any desired manner where possible and expedient.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of one ormore preferred embodiments when considered in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a collision detection device asper a first exemplary embodiment of the present invention.

FIG. 2 is a schematic sectional view of a collision detection device asper a second exemplary embodiment of the present invention.

A detailed description of the exemplary embodiments of the presentinvention follows with reference to the figures.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic sectional view of a collision detection device1 as per a first exemplary embodiment of the present invention. Thecollision detection device 1 is intended for a motor vehicle front endof a motor vehicle, in particular a passenger motor vehicle, fordetecting a collision with a pedestrian. The collision detection device1 has a pressure measurement chamber 3 which is formed by an elasticallydeformable tube 5 composed, for example, of a silicone material. Thetube 5 is supported against a bumper crossmember 7, that is to sayagainst a front side 71 of the bumper crossmember 7. The front side 71of the bumper crossmember 7 is a first support surface according to thepresent invention.

Furthermore, in the vertical direction of the vehicle, the tube 5 issupported downwardly against a projection 73 with a support surface 72which supports the tube 5 from below and which forms a second supportsurface according to the present invention.

The motor vehicle front end also has a bumper cover 11, wherein arrangedbetween the bumper cover 11 and the bumper crossmember 7 is anenergy-absorption element 9, that is to say a pedestrian protectionelement, which consists of a plastically deformable foam. Theenergy-absorption element 9 surrounds the tube 5 in particular from thefront and from above. The tube 5 is supported against the bumpercrossmember 7 with the projection 73, which is fastened to saidcrossmember in a flexurally rigid manner, only rearwardly (from behind)and downwardly (from below). Accordingly, the tube is arranged betweenthe bumper crossmember 7, the projection 73 and the energy-absorptionelement 9.

Connected to the pressure measurement chamber 3 of the tube 5 is atleast one pressure sensor which is able to detect a change in pressurein the pressure measurement chamber 3, the latter being filled with airunder atmospheric pressure. A change in pressure in the pressuremeasurement chamber 3 is caused by a deformation of the tube, saiddeformation bringing about a change in volume of the pressuremeasurement chamber 3.

Below, an effect and function of the collision detection device 1 as perthe first exemplary embodiment are described.

In the event of a front-end collision of the motor vehicle (or the motorvehicle front end) with a pedestrian 13, a collision force acts on theenergy-absorption element 9 obliquely from the front and above obliquelydownwardly and rearwardly owing to the height and the center of gravityof the pedestrian 13, said center of gravity being located well abovethe tube 5. The energy-absorption element 9 transmits this force to thetube 5. A direction of action of the collision force is illustrated inFIG. 1 by an arrow. Since the tube 5 is supported both rearwardly in thelongitudinal direction of the vehicle and downwardly in the verticaldirection of the vehicle, a deformation of the tube 5 obliquelydownwardly and rearwardly by way of the collision force, which istransmitted by the energy-absorption element 9 obliquely from the frontand above, is promoted. Thus, a quicker and/or a clearer or bettercollision detection signal—that is to say a change in pressure—isgenerated. Furthermore, the tube 5 can be deformed easily since it isnot supported from above by the structural element 7.

The collision-induced deformation of the tube 5 brings about the changein pressure in the pressure measurement chamber 3, which change inpressure is in turn able to be detected by a pressure sensor. Thequicker and more intensely the tube 5 is deformed during the collisionwith the pedestrian, the earlier and better a collision detection signalcan be obtained by the collision detection device and the earliersuitable active pedestrian protection measures, such as for example theraising of a front flap or the triggering of a front windshield airbagor pedestrian protection airbag, can accordingly be directed anddeployed.

A second exemplary embodiment of the present invention is describedbelow with reference to FIG. 2, wherein, in particular, the differenceswith the first exemplary embodiment are addressed and any features incommon with the first exemplary embodiment are not described again.

As is shown in FIG. 2, a motor vehicle front end has a bumpercrossmember 7, on the front side of which an energy-absorption element 9is arranged. The motor vehicle front end also has a bumper cover 11.

In contrast with the first exemplary embodiment, in the second exemplaryembodiment, an inner side 111 of the bumper cover 11 forms a firstsupport surface according to the present invention, and a projection113, which is connected fixedly in terms of torque to the bumper cover11, in particular at a lower side 112 of the projection 113, forms asecond support surface according to the present invention. In otherwords, a tube 5, together with its pressure measurement chamber 3, issupported forwardly (from in front) and upwardly (from above) by theinner side 111 of the bumper cover 11 and the projection 113 connectedthereto, that is to say the lower side 112 of the projection 113. Thetube 5 is furthermore surrounded by the energy-absorption element 9.

A description of the function and manner of operation of the collisiondetection device 1 as per the second exemplary embodiment of the presentinvention follows with reference to FIG. 2.

Analogously to the first exemplary embodiment, in the event of afront-end collision of the motor vehicle with a pedestrian 13, acollision force acts on the motor vehicle front end, that is to say thebumper cover 11 and the energy-absorption element 9 which is arrangedtherebehind and which is supported against the bumper crossmember 7,from the front and above rearwardly and downwardly. Consequently, thetube 5 is pushed against the adjacent energy-absorption element 9 fromthe front and above rearwardly and downwardly by the lower side 112 ofthe projection 113 and by the inner side 111 of the bumper cover 11, anddeformed as a result. Analogously to the first exemplary embodiment, inthe second exemplary embodiment, improved force transmission of thecollision force, acting obliquely from the front and above, to the tube5 is realized according to the invention by way of the two supportsurfaces formed in different directions, as a result of which thedeformation of said tube is promoted and a collision detection signal isaccordingly generated in a quicker and better manner.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

What is claimed is:
 1. A collision detection device for a motor vehicle that detects a collision with a pedestrian, comprising: a pressure measurement chamber which is formed by a tube; and a flexurally rigid structural element, wherein the tube is formed and arranged so as to be deformable in a collision-induced manner and is supported against the structural element in a direction transverse to a vertical direction of the vehicle and in precisely one vertical direction of the vehicle.
 2. The collision detection device as claimed in claim 1, wherein the structural element has a first support surface which extends substantially parallel to the vertical direction of the vehicle and has a second support surface which extends transversely to the vertical direction of the vehicle.
 3. The collision detection device as claimed in claim 2, wherein the second support surface is formed either on a top side or a bottom side of a projection which is connected to the first support surface in a flexurally rigid manner or which is formed integrally with the first support surface or the structural element, and a lower side of the tube or an upper side of the tube is supported against the projection.
 4. The collision detection device as claimed in claim 3, wherein the first support surface is formed behind the tube in a collision direction, and the second support surface is formed below the tube.
 5. The collision detection device as claimed in claim 2, wherein the first support surface is formed behind the tube in a collision direction, and the second support surface is formed below the tube.
 6. The collision detection device as claimed in claim 4, wherein the structural element is a crossmember element, the first support surface is formed on an outer side of the crossmember element, and the second support surface is formed on a projection which is connected fixedly in terms of torque to the crossmember element or which is integrally formed with the first support surface or the crossmember element.
 7. The collision detection device as claimed in claim 6, wherein the crossmember element is a bumper crossmember.
 8. The collision detection device as claimed in claim 2, wherein the first support surface is formed in front of the tube in a collision direction, and the second support surface is formed above the tube.
 9. The collision detection device as claimed in claim 3, wherein the first support surface is formed in front of the tube in a collision direction, and the second support surface is formed above the tube.
 10. The collision detection device as claimed in claim 8, wherein the structural element is a vehicle outer skin, the first support surface is formed on an inner side of the vehicle outer skin, and the second support surface is formed on a projection which is connected fixedly in terms of torque to the vehicle outer skin or which is integrally formed with the first support surface or the vehicle outer skin.
 11. The collision detection device as claimed in claim 10, wherein the vehicle outer skin is a bumper cover.
 12. The collision detection device as claimed in claim 2, wherein the second support surface extends along an entire effective length of the tube, or the second support surface extends sectionally along the effective length of the tube.
 13. The collision detection device as claimed in claim 1, wherein the tube is surrounded at least partially by a plastically deformable energy-absorption element, or is at least adjacent to the energy-absorption element, and the energy-absorption element is arranged in front of or behind the structural element in the collision direction.
 14. The collision detection device as claimed in claim 13, wherein the energy-absorption element is a pedestrian protection device.
 15. The collision detection device as claimed in claim 13, wherein the energy-absorption element bears against the tube, or comes into abutment with said tube in the event of a collision, on sides of the tube which are not supported.
 16. The collision detection device as claimed in claim 15, wherein the sides of the tube are not supported in a longitudinal direction of the vehicle and in a vertical direction of the vehicle.
 17. The collision detection device as claimed in claim 1, wherein the collision detection device is configured for a front end or a rear end of the motor vehicle. 